Maternal Diet, Arsenic Exposure, and Pregnancy Outcomes in Bangladesh

Abstract

This study investigated the relationship between maternal diet, arsenic exposure and birth outcomes in the Bangladeshi administrative regions of Sirajdikhan and Pabna Sadar. First, the study assessed the validity of a dish-based food frequency questionnaire (FFQ) by comparing it with two 3-day food diaries (FD). Food and nutrient intakes measured by FFQ and FD were compared using Pearson’s and Spearman’s correlation, paired t-test, percent difference, cross-classification, weighted Kappa, and Bland–Altman analysis. Results suggested that the FFQ exhibited good ability to assess and rank long-term dietary intake for most food groups and nutrients. Using this FFQ, the study then evaluated the relationship between long-term dietary habits and total arsenic concentration in toenail clippings. Associations between natural log-transformed consumption of individual food items and temporally matched natural log-transformed toenail arsenic concentration were quantified using general linear models that accounted for arsenic in the primary drinking water source and other potential confounders. Toenail arsenic was positively associated with consumption of several vegetable, fish and meat items and was negatively associated with consumption of rice, cereal, fruits, and milk based food items. The last part of the study used causal mediation analysis to investigate the causal pathway between diet, arsenic and fetal growth factors associated with birth weight. Mediating analysis showed significant natural indirect effects by toenail arsenic in the relationship between absolute fat, carbohydrate and fiber intake on gestational age at birth, specifically 3% (95% CI: 1%-6%) of the association between carbohydrate intake and gestational age at birth was mediated by change in toenail arsenic level, while the mediating effect was 6% (95% CI: 1%-9%) and 10% (95% CI: 4%-13%) for absolute fat and fiber intake, respectively. After adjusting for total energy, no significant mediating effect was found, suggesting the absolute amount of arsenic exposure rather than the arsenic level in relationship to total energy intake was a more important factor to consider when understanding the negative implication of arsenic on fetal growths.